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ISSUE45 PUBLISHED

BUDGET LENSES FOR ASTROPHOTOGRAPHY

This image of the Orion Nebula was taken, not with a telescope, but with a camera lens older than myself attached to an entry-level modded DSLR camera. The lens in question is a 200mm SMC Takumar f4. It was manufactured sometime in the early 1970s and I picked it up off eBay for £22. The total exposure time is about 40 minutes, enough to show hints of structure in the larger dust lane the nebula is embedded in. The internal lens iris was used to stop the lens down to f5.6, which gives better star shapes in the corners. However, this has resulted in large diffraction spikes on the bright stars, for this particular shot I’d have preferred to use a step-down ring as a front aperture mask, a cheap and simple way of producing circular stars.

Vintage lenses like this can provide a very cost-effective route into astrophotography. I’ve used a number of different ones of between 24mm and 200mm focal length for a variety of shots. By shopping around carefully I’ve amassed quite a collection, my cheapest cost me £18 while the most I’ve spent was £65. Below are some of the better images I've taken with them.

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This slightly wider shot was taken with an SMC Takumar 135mm f2.5 lens (cost £50) at f4, it’s also just over 40 minutes of data. On the left are the three bright stars of Orion’s Belt. Nothing quite divides astrophotographers like diffraction spikes but in this particular shot I quite like them – they highlight the naked eye visible stars which helps place the scene in context. This particular lens has an eight bladed iris, giving eight tight diffraction spikes. On the left are the aptly named Flame and Horsehead nebulae, while the Orion Nebula is on the right. The Horsehead and Orion nebulae are both star-forming regions but the former is at a much earlier stage of evolution. In the Horsehead newly formed stars are hidden by the concentrated dust clouds, while fast stellar winds and radiation pressure the hot blue stars in the Orion Nebula are in the process of expelling most of the gas and dust back into space. Shooting at f4 rather than f5.6 has doubled the amount of light reaching the camera sensor, as a result more structure is visible in the background dust.

 

Prior to upgrading to the f2.5 lens I was using an even older and cheaper 135mm lens - an f3.5 Super-Takumar from the mid 1960s - which cost me just £18.

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This is just 30 minutes of data showing the Heart & Soul Nebulae along with the Double Cluster, in the constellation Perseus. The field of view with this lens on an APS-C camera is about 9 by 6 degrees, for scale each component of the Double has about the same apparent size as a full Moon. There are a few enormous nebulae like this hiding just out of sight.

 

The image was taken with the lens aperture wide open, at f3.5, giving circular stars but increasing distortion in the corners (it’s more apparent when viewing the image at a larger size). Shooting at f4.5 gives better results but requires longer exposure times to reach the same depth.

 

For a wider view of the same region I used a borrowed Carl-Zeiss 35mm f2.4 lens at f5.6.

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The view is centred on the w-shaped constellation of Cassiopeia, the diffraction spikes help it stand out from the mass of stars in the Milky Way. Also visible near the centre of frame is the Pacman nebula, at this scale its name is merited.

 

I’ve heard only good things about the Carl-Zeiss lenses but they are quite expensive on the second-hand market. The Takumar lenses by Asahi Optics tend to offer better value for money. Here’s another shot taken with another Takumar lens, a 50mm f1.4 at f4.

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This image is about 1h30m on the busy region of the constellation Cygnus. The bright star on the left is Deneb, a distant blue giant about 100,000 times brighter than our Sun. Numerous nebulae are in view, including the North America, Pelican and the Veil supernova remnant.

 

Prior to getting the 50mm Takumar lens I used a new 50mm f1.8 Canon lens, which cost about the same amount. It’s not quite as good as the vintage glass for AP, bright stars produce larger artefacts as can be seen in the shot of Orion below and the corner stars are not quite as good at f4, but it has the advantage of auto-focus for daytime shots.

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Another family of cheap lenses worth mentioning are the family of kit lenses commonly supplied with new cameras. While not ideal tools for AP they are still capable of producing good results, as this wider view of Cygnus shows.

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This particular shot is just 20 minutes of data taken with an STM lens at 18mm focal length and f5.0.

 

Vintage lenses giving a wide field of view are rare, making the kit lens the best budget option for Milky Way shots, but I have used a Vivitar 24mm f2.8 lens that was gifted to me.

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Shot at f5.6, this view shows the Hyades star cluster at left with the prominent red giant Aldebaran in front of them, the Pleiades and the California nebula. On close examination the lens appears to be heavily infested with fungus and has since been placed in quarantine. We really don’t know if life is common or scarce in cosmic vistas such as the one shown above, but it is certainly present in the optic used to take it.

 

All these images were taken using a cheap tracking mount, an EQ3-2, from a dark sky site.

Vintage Lens Tips

Vintage lenses can offer good image quality for AP at affordable prices, and also offer some ergonomic advantages compared to modern auto-focus lenses. The focus rings are larger and offer more resistance making them less fiddly to adjust - with my Canon lenses I have to tape or blu-tac the focus ring to stop it creeping out of position. However, there are a few things to watch out for if you are considering buying one.

 

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